Washing machine

ABSTRACT

A washing machine capable of preventing a magnet, which detects a number of rotations of a washing shaft, from being removed from a predetermined position. The washing machine includes a drive motor to generate a rotating force. A washing shaft is rotated by the drive motor. A belt and a shaft pulley transmit the rotating force from the drive motor to the washing shaft. A magnet is mounted to the shaft pulley to rotate along with the shaft pulley. A magnetic sensor detects a number of rotations of the washing shaft, in response to a change in a magnetic field produced by the magnet. A locking unit is mounted at a first end thereof to the magnet, and at a second end thereof to the shaft pulley. Therefore, even when the vibrations caused by operations of the washing machine are transmitted to the magnet for a lengthy period of time, the magnet is connected to the shaft pulley by the locking unit without being removed from a predetermined position.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 2003-72929, filed on Oct. 20, 2003 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates, in general, to washing machines and, more particularly, to a washing machine capable of preventing a magnet, which is provided in a power transmission unit to detect a number of rotations of a washing shaft, from being removed from a predetermined position.

2. Description of the Related Art

Generally, a washing machine is an appliance that washes laundry by rotating a rotary tub and/or a pulsator which are installed in a water tub, thus performing a washing operation, a rinsing operation, and a spin-drying operation.

The washing machine includes a cabinet, having a water tub to contain wash water therein located in the cabinet. A rotary tub is rotatably set in the water tub. The pulsator is installed in the rotary tub to agitate the laundry in the wash water.

Further, the washing machine includes a drive motor and a power transmission unit. The drive motor is provided under the water tub to drive the rotary tub and the pulsator. A rotating force of the drive motor is transmitted to the power transmission unit via a belt. The power transmission unit transmits the rotating force to the rotary tub and/or the pulsator.

The power transmission unit includes a washing shaft, a spin-drying shaft, and a clutch unit. The washing shaft transmits the rotating force from the drive motor to the pulsator. The spin-drying shaft transmits the rotating force from the drive motor to the rotary tub. The clutch unit controls power transmission between the washing shaft and the spin-drying shaft, to allow the spin-drying shaft to selectively rotate.

The power transmission unit also includes a shaft pulley. The shaft pulley is mounted to a lower end of the washing shaft, so that the rotating force is transmitted from the drive motor to the shaft pulley. A magnet is provided at a predetermined position adjacent to the shaft pulley to rotate along with the shaft pulley. A magnetic sensor senses a change in a magnetic field produced by the magnet, thus detecting a number of rotations of the washing shaft.

However, in the conventional washing machine, the magnet is secured to a predetermined position of the power transmission unit using an adhesive, and rotates along with the washing shaft. Thus, the conventional washing machine has a problem in that a strength of the adhesive is weakened when vibrations caused by operations of the washing machine have been transmitted to the magnet for a lengthy period of time, and thereby the magnet may be removed from the predetermined position of the power transmission unit.

SUMMARY OF THE INVENTION

Accordingly, it is an aspect of the present invention to provide a washing machine capable of preventing a magnet from being removed from a predetermined position even when the washing machine has been used for a lengthy period of time.

Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

The foregoing and/or other aspects of the present invention are achieved by providing a washing machine comprising a drive motor to generate a rotating force, a washing shaft rotated by the drive motor, a belt and a shaft pulley to transmit the rotating force from the drive motor to the washing shaft, a magnet mounted on the shaft pulley to rotate along with the shaft pulley, and a locking unit mounted at a first end thereof to the magnet, and at a second end thereof to the shaft pulley, thus locking the magnet to the shaft pulley.

According to an aspect of the invention, the washing machine further comprises a magnetic sensor to sense a change in a magnetic field produced by the magnet as the magnet rotates, to detect a number of rotations of the shaft pulley.

In another aspect of this embodiment, the shaft pulley comprises a through hole which axially extends through the shaft pulley. The locking unit comprises a first locking part provided on the first end of the locking unit to be supported by the magnet, and a second locking part provided on the second end of the locking unit. The second locking part passes through the through hole of the shaft pulley to be supported by a portion around the through hole of the shaft pulley.

In another aspect of this embodiment, the magnet and the locking unit are formed of an annular shape to allow the washing shaft to pass through the magnet and the locking unit, and the magnet comprises a seating recess on an inner circumference thereof, wherein the first locking part of the locking unit is mounted on the seating recess.

In another aspect of this embodiment, the first locking part is projected from an outer circumferential surface of the locking unit, and the second locking part may extend toward a center of the locking unit.

In another aspect of this embodiment, the second locking part may be made of a material which is elastically deformed, so that the second locking part is elastically deformed when passing through the through hole, and elastically restores an original shape of the second locking part to be supported by the portion around the through hole of the shaft pulley after passing through the through hole.

In another aspect of this embodiment, the magnet is provided so that north and south poles thereof are alternately arranged in a circumferential direction of the magnet, to allow the magnetic field to be changed as the magnet rotates.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a sectional view of a washing machine, according to an embodiment of the present invention;

FIG. 2 is a sectional view to show a power transmission unit and an rpm detecting unit included in the washing machine of FIG. 1; and

FIG. 3 is an exploded perspective view of the rpm detecting unit of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures.

In FIG. 1, a washing machine according to the present invention comprises a cabinet 10, a water tub 11 installed in the cabinet 10 to contain wash water therein and a rotary tub 12 rotatably set in the water tub 11, wherein the water tub 11 is supported at an outer surface of a lower portion thereof by suspension units 13 which are interiorly provided on an upper portion of the cabinet 10. A water supply unit 14 is provided at a predetermined position above the water tub 11 to feed the wash water into the water tub 11, and comprises a water supply pipe 14a and a water supply valve 14b. Further, a drain unit 15 is provided at a predetermined position under the water tub 11 to discharge the wash water outside of the water tub 11, and comprises a drain pipe 15 a, a drain valve 15 b, and a drain motor (not shown).

A pulsator 16 is provided in the rotary tub 12, and rotates in alternating directions to generate wash water currents. A drive unit is installed in a space between a bottom of the water tub 11 and a bottom of the cabinet 10 to rotate the rotary tub 12 and the pulsator 16. The drive unit comprises a drive motor 17, a power transmission unit 20, and a belt 18. The drive motor 17 generates a rotating force when an electric power is applied to the drive motor 17. The power transmission unit 20 transmits the rotating force of the drive motor 17 to the pulsator 16 and/or the rotary tub 12. The belt 18 connects the drive motor 17 to the power transmission unit 20, to transmit the rotating force from the drive motor 17 to the power transmission unit 20.

In FIGS. 2 and 3, the power transmission unit 20 comprises first and second washing shafts 21 and 22, which are aligned in series to transmit the rotating force from the drive motor 17 to the pulsator 16. In this case, the first washing shaft 21 is provided at a lower portion of the power transmission unit 20, and the second washing shaft 22 is provided at an upper portion of the power transmission unit 20. Hollow spin-drying shafts 23 a and 23 b are rotatably fitted over the second and first washing shafts 22 and 21, respectively, to rotate the rotary tub 12. Further, a cylindrical brake drum 24 which stops the rotary tub 12, is provided at a predetermined position of the spin-drying shafts 23 a and 23 b, and rotates along with the spin-drying shafts 23 a and 23 b. A brake band 25 constituting a brake unit together with the brake drum 24 is provided on an outer surface of the brake drum 24. In order to transmit the rotating force from the drive motor 17 through the belt 18 to the first washing shaft 21, the drive motor 17 and the first washing shaft 21 comprise pulleys 17 a and 21 a, respectively. The pulley mounted on the drive motor 17 is designated as a motor pulley 17 a, while the pulley mounted on the first washing shaft 21 is designated as a shaft pulley 21 a.

The power transmission unit 20 further comprises a planetary reduction gear unit 40, a clutch unit 50, and housings 27 a and 27 b. The planetary reduction gear unit 40 is installed in the brake drum 24, and transmits the rotating force from the first washing shaft 21 to the second washing shaft 22 while reducing a speed of the first washing shaft 21. The clutch unit 50 is mounted to a lower end of the spin-drying shaft 23 b to control power transmission between the first washing shaft 21 and the spin-drying shaft 23 b. The housings 27 a and 27 b are exteriorly mounted to the bottom of the water tub 11, and rotatably support the spin-drying shafts 23 a and 23 b. Further, a brake lever 29 and a clutch lever 30 are provided at a side of the housings 27 a and 27 b, and are rotatably mounted to predetermined portions of a support pin 28 to operate the clutch unit 50. The brake lever 29 and the clutch lever 30 are constructed to operate in conjunction with the drain motor (not shown), to open the drain valve 15 b.

The housings 27 a and 27 b comprise an upper housing 27 a which is mounted to the bottom of the water tub 11, and a lower housing 27 b which surrounds the brake drum 24 and is mounted at an upper end of the lower housing 27 b to the upper housing 27 a. Further, the spin-drying shafts 23 a and 23 b comprise an upper spin-drying shaft 23 a and a lower spin-drying shaft 23 b. The upper spin-drying shaft 23 a is provided at an upper portion of the brake drum 24, having an upper end thereof extending into the water tub 11 to be connected to the water tub 12. The lower spin-drying shaft 23 b is provided at a lower portion of the brake drum 24. The upper and lower spin-drying shafts 23 a and 23 b are rotatably supported by the upper and lower housings 27 a and 27 b using bearings 31. The first and second washing shafts 21 and 22 are rotatably supported by the lower and upper spin-drying shafts 23 b and 23 a, respectively, using a plurality of oilless bearings 32.

The first washing shaft 21 is mounted, at a lower end thereof, to the shaft pulley 21 a so that the power is transmitted from the drive motor 17 to the first washing shaft 21, with an upper end of the first washing shaft 21 extending into the brake drum 24. Further, the second washing shaft 22 extends, at a lower end thereof, into the brake drum 24, while extending, at an upper end thereof, into the rotary tub 12 to be connected to the pulsator 16.

The planetary reduction gear unit 40 installed in the brake drum 24 comprises a sun gear 41, a plurality of planetary gears 42, an internal gear 43, and a carrier 44. The sun gear 41 is provided on the upper end of the first washing shaft 21. The plurality of planetary gears 42 are arranged around the sun gear 41. The internal gear 43 is provided on an inner surface of the brake drum 24. The carrier 44 is mounted to the lower end of the second washing shaft 22. In this case, each of the planetary gears 42 engages, at a first side thereof, with the sun gear 41, while engaging, at a second side thereof, with the internal gear 43. A planetary gear shaft 45 to support each of the planetary gears 42 is supported by the carrier 44 and revolves around the sun gear 41. When the brake drum 24 stops and the first washing shaft 21 rotates, the above-mentioned construction allows the plurality of planetary gears 42 to rotate on their own central axes together with the sun gear 41 while revolving along the internal gear 43. Further, when the plurality of planetary gears 42 revolve around the sun gear 41, the carrier 44 connected to the plurality of planetary gears 42 via the planetary gear shafts 45 rotates at a revolving speed of the plurality of planetary gears 42, thus rotating the second washing shaft 22 while reducing a speed of the second washing shaft 22.

The clutch unit 50, which controls the power transmission between the lower spin-drying shaft 23 b and the first washing shaft 21, includes a transmission member 51 and a clutch spring 53. The transmission member 51 comprises a same diameter as an outer diameter of the lower spin-drying shaft 23 b, and is mounted to an outer surface of the first washing shaft 21 to be adjacent to a bottom of the lower spin-drying shaft 23 b. The clutch spring 53 is formed of a coil shape to wrap around outer surfaces of the lower spin-drying shaft 23 b and the transmission member 51. A cylindrical sleeve 54 is provided on an outer surface of the clutch spring 53. The sleeve 54 tightens or loosens the clutch spring 53 to control the power transmission between the lower spin-drying shaft 23 b and the first washing shaft 21. In this case, the clutch spring 53 is mounted at an upper portion thereof to the lower spin-drying shaft 23 b, and at a lower end thereof to an inner surface of the sleeve 54, thus tightening or loosening the transmission member 51 by a rotation of the sleeve 54. The sleeve 54 rotates by an operation of the clutch lever 30.

Further, the washing machine according to the present invention comprises an rpm detecting unit 60 to detect a number of rotations of the washing shaft.

The rpm detecting unit 60 comprises a magnet 61, a magnetic sensor 62, and a locking unit 63. The magnet 61 rotates along with the first washing shaft 21 to produce a magnetic field. The magnetic sensor 62 detects the number of rotations of the first washing shaft 21, in response to a change in the magnetic field produced by the magnet 61. The locking unit 63 locks the magnet 61 to the shaft pulley 21 a.

The magnet 61 is mounted to the shaft pulley 21 a, and is formed of an annular shape to allow the first washing shaft 21 to pass through the magnet 61 and to be mounted to the shaft pulley 21. Further, the magnet 61 is provided so that north and south poles thereof are alternately arranged in a circumferential direction of the magnet 61. Thus, as the magnet 61 rotates, a magnetic field sensed by the magnetic sensor 62 is changed.

In order to mount the magnet 61 to the shaft pulley 21 a using the locking unit 63, a plurality of through holes 21 b are provided on the shaft pulley 21 a to axially extend through the shaft pulley 21 a. Further, the locking unit 63 comprises first and second locking parts 63 a and 63 b. The first locking parts 63 a are projected from an outer circumferential surface of a first end of the locking unit 63 to be supported by the magnet 61, and the second locking parts 63 b are provided on a second end of the locking unit 63 to extend toward a center of the locking unit 63. The second locking parts 63 b are elastically deformed when passing through the through holes 21 b, and elastically restore original shapes thereof to be supported by edges around the through holes 21 b after passing through the through holes 21 b. The magnet 61 comprises seating recesses 61a on an inner circumference thereof, so that the first locking parts 63 a of the locking unit 63 located in the corresponding seating recesses 61 a of the magnet 61.

The magnetic sensor 62 is mounted to a predetermined portion of the lower housing 27 b to extend downward, with an end of the magnetic sensor 62 contacting with an outer circumference of the magnet 61 to detect change in the magnetic field due to the rotation of the magnet 61. According to the embodiment, a hall sensor using a hall effect is used as the magnetic sensor 62.

The operation and operational effects of the washing machine according to the present invention will be described in the following.

When a washing operation is performed, the drain valve 15 b, provided at a predetermined position under the water tub 11, is closed. Further, because the clutch lever 30 operating in conjunction with the brake lever 29 rotates in a certain direction, and then is maintained at the rotated state by a coil spring 28 a fitted over the support pin 28, the brake band 25 is tightened to limit a rotation of the brake drum 24. At this time, the sleeve 54 rotated by the clutch lever 30 loosens the clutch spring 53, so that there is no power transmission between the lower spin-drying shaft 23 b and the transmission member 51.

In such a state, when the first washing shaft 21 is rotated by the drive motor 17, the planetary gears 42 provided in the brake drum 24 rotate while engaging with the sun gear 41 of the first washing shaft 21. At this time, the plurality of planetary gears 42 revolve around the sun gear 41 while rotating on their own central axes, because the internal gear 43 provided on the inner surface of the brake drum 24 is fixed. As the plurality of planetary gears 42 revolve around the sun gear 41, the carrier 44 rotates. Thus, the second washing shaft 22 rotates while the rotating speed thereof is reduced. Since the pulsator 16 provided in the rotary tub 12 is connected to the second washing shaft 22, the pulsator 16 rotates at a low speed to agitate laundry in wash water. Thus, only the first and second washing shafts 21 and 22 rotate, so that the pulsator 16 rotates while the rotary tub 12 is stopped, to perform the washing operation.

When the washing operation is completed, a rinsing operation is performed. During the rinsing operation, water supply operations and water drain operations are executed several times. After the rinsing operation is completed, a spin-drying operation is performed. To execute the water drain operation, the drain valve 15 b is opened by the drain motor (not shown). At this time, the brake lever 29 and the clutch lever 30 operating in conjunction with the drain motor (not shown) are pulled, so that the brake band 25 is released, thereby releasing a brake of the brake drum 24. Further, the sleeve 54 is released by the rotation of the clutch lever 30. Thus, the sleeve 54 rotates by an elastic force of the clutch spring 53 to restore an original state thereof, so that the clutch spring 53 tightens an outer surface of the transmission member 51. The transmission member 51, rotating along with the first washing shaft 21, is connected to the lower spin-drying shaft 23 b via the clutch spring 53.

When the drive motor 17 rotates in such a state, the lower spin-drying shaft 23 b rotates together with the first washing shaft 21. Thus, the upper and lower spin-drying shafts 23 a and 23 b and the first and second washing shafts 21 and 22 simultaneously rotate, and thereby causing the pulsator 16 and the rotary tub 12 to rotate simultaneously, thus performing the spin-drying operation. In this case, the sun gear 41 and the brake drum 24 rotate at a same speed, so that the planetary gears 42 revolve around the sun gear 41 while stopping rotating on their own central axes. Thus, the second washing shaft 22 and the upper spin-drying shaft 23 a rotate at a same speed.

When the spin-drying operation is completed, the clutch lever 30 is released by the operation of the drain motor (not shown). At this time, the brake band 25 is tightened by the rotation of the clutch lever 30, thus applying the brake drum 24. Further, the clutch spring 53 is loosened, thereby preventing the power from being transmitted to the lower spin-drying shaft 23 b.

According to the present invention, although vibrations are repeatedly transmitted to the magnet 61 while the rotating force is transmitted from the drive motor 17 to the first washing shaft 21 due to the operations of the washing machine, the first locking parts 63 a of the locking unit 63 are mounted on the seating recesses 61 a of the magnet 61, and the second locking parts 63 b of the locking unit 63 pass through the through holes 21 b and are supported by the edges around the through holes 21 b. Thus, the magnet 61 is mounted on the shaft pulley 21 a without being removed from a predetermined position.

As is apparent from the above description, the present invention provides a washing machine, which is constructed so that a magnet to detect a number of rotations of a washing shaft is mounted to a shaft pulley using a locking unit, to prevent the magnet from being removed from a predetermined position, even when vibrations caused by operations of the washing machine are transmitted to the magnet for a lengthy period of time.

Although an embodiment of the present invention has been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents. 

1. A washing machine, comprising: a drive motor to generate a rotating force; a washing shaft rotated by the drive motor; a belt and a shaft pulley to transmit the rotating force from the drive motor to the washing shaft; a magnet mounted on the shaft pulley to rotate along with the shaft pulley; and a locking unit mounted at a first end thereof to the magnet, and at a second end thereof to the shaft pulley, to lock the magnet to the shaft pulley.
 2. The washing machine of claim 1, further comprising: a magnetic sensor to sense a change in a magnetic field produced by the magnet as the magnet rotates, to detect a number of rotations of the shaft pulley.
 3. The washing machine of claim 1, wherein the shaft pulley comprises a through hole which axially extends through the shaft pulley, and the locking unit comprises: a first locking part provided on the first end of the locking unit to be supported by the magnet; and a second locking part provided on the second end of the locking unit, the second locking part passing through the through hole of the shaft pulley to be supported by a portion around the through hole of the shaft pulley.
 4. The washing machine of claim 3, wherein the magnet and the locking unit are formed of an annular shape, to allow the washing shaft to pass through the magnet and the locking unit, and the magnet comprises a seating recess on an inner circumference thereof, wherein the first locking part of the locking unit is mounted on the seating recess.
 5. The washing machine of claim 4, wherein the first locking part is projected from an outer circumferential surface of the locking unit, and the second locking part extends toward a center of the locking unit.
 6. The washing machine of claim 3, wherein the second locking part comprises a material which is elastically deformed, wherein the second locking part is elastically deformed when passing through the through hole, and elastically restores an original shape of the second locking part to be supported by the portion around the through hole of the shaft pulley after passing through the through hole.
 7. The washing machine of claim 2, wherein the magnet is provided so that north and south poles thereof are alternately arranged in a circumferential direction of the magnet, to allow the magnetic field to be changed as the magnet rotates.
 8. A washing machine, comprising: a drive unit to operate the washing machine and comprising a washing shaft and a shaft pulley, wherein the shaft pulley transmits a rotational force to the washing shaft, to rotate the washing shaft; and an rpm detecting unit to detect the number of rotations of the washing shaft and comprising a magnet and a locking unit, wherein the locking unit locks the magnet to the shaft pulley to prevent the magnet from detaching from the shaft pulley.
 9. The washing machine of claim 8, wherein the magnet and the locking unit are formed of an annular shape, to allow the washing shaft to pass through the magnet and the locking unit.
 10. The washing machine of claim 8, wherein: the shaft pulley comprises a through hole which axially extends through the shaft pulley, and the locking unit comprises: a first locking part provided on a first end of the locking unit to be supported by the magnet; and a second locking part provided on a second end of the locking unit, wherein the second locking part passes through the through hole of the shaft pulley to be supported by the shaft pulley.
 11. The washing machine of claim 8, the rpm detecting unit further comprises a magnetic sensor to sense a difference in a magnetic field produced by the magnet as the magnet rotates, thereby detecting the number of rotations of the shaft pulley.
 12. The washing machine of claim 10, wherein the magnet comprises a seating recess on an inner circumference thereof, wherein the first locking part is mounted on the seating recess.
 13. The washing machine of claim 10, wherein the second locking part comprises a material which is elastically deformed, wherein the second locking part is elastically deformed when passing through the through hole, and elastically restore an original shape of the second locking part to be supported by a portion around the through hole.
 14. The washing machine of claim 11, wherein the magnet is provided so that north and south poles thereof are alternately arranged in a circumferential direction of the magnet, to allow the magnetic field to be changed as the magnet rotates. 